1. Field of the Invention
The present invention relates to apparatus and methods for structured data storage, retrieval, and utilization, and more particularly, to storage-based techniques for implementing virtually instantaneous playback of audio effects data in synchronization with playback of associated video data in an audiovisual effects processing system.
2. Art Background
The development of audiovisual works often involves processing of the audio portions of a work independent of the processing of the corresponding video portions of the work. In the film industry, for example, it is common practice to substitute synthetic sounds, produced in a sound laboratory, for the actual sounds that were recorded during recording of the visual portions of a film. These synthetic audio portions are then combined with the associated video portions of the film, resulting in a single audiovisual work, on the basis of time codes which are used to relate each particular audio portion (i.e., each individual sound) to the video portion related to that sound.
The relation between a multiplicity of recorded sounds and their video counterparts is commonly represented by an edit decision list (EDL), which lists each effect along with the time in the work at which each effect is utilized. A hypothetical EDL might reflect, for example, that a door would slam at one minute, five seconds, and 6 frames into the work, and that a footstep would be heard at one minute, six seconds, and 15 frames. When the visual portion of the work is reviewed, the sounds listed in the EDL must be accessed and played at the particular times identified in the EDL. In playing these sounds, the margin for error in playback time is very small. In particular, a sound must be played back with a near-zero delay (i.e., instantaneously) from the time at which that sound is requested. As used herein, the term "instantaneous" refers to delays not noticeable to the typical human, such as the access times of many volatile memory devices such as commonly available random access memory (RAM), as contrasted with the access times of storage devices such as hard disk drives which are often noticeable by a user.
Presently existing designs for such film effects systems impose severe practical limitations upon the functionality, and therefore upon the value, of these systems. These limitations are best understood by examining the procedures involved in the use of such systems by audio engineers. A typical feature-length movie contains at least 50 scenes, each of which might contain hundreds of individual sound effects. To accommodate the audio data representing these sound effects, present professional systems are considered to require a minimum of 250 megabytes of RAM, and such systems often provide substantially more memory for instantaneous playback, typically in excess of a gigabyte.
Before editing a particular audiovisual sequence with present systems, all the sound effects that may potentially be used in that sequence must first be loaded into RAM. This process often requires load times in excess of one hour for lengthy sequences. Pre-loading is customarily required so that sound engineers do not have to plan ahead to load each effect just prior to their utilization of that effect, and to load only the effects needed for the sequence. Additionally, the basic nature of the sound engineering process requires frequent rearrangement of effects, continual reassignment of effects to different portions of a scene, and repeated addition and removal of whole effects to and from a scene. Consequently, an effects system that did not pre-load all effects for a particular scene would simply be impracticable.
The use of RAM in such systems has several inherent problems. First, the substantial quantity of RAM required is very expensive, particularly when compared to the cost of alternative techniques for data storage. The RAM used in professional audio effects systems is high-end static RAM, which is more costly than typical dynamic RAM used in computer systems. In the present market, a gigabyte of such RAM may cost between seven and ten thousand dollars, as compared with approximately two hundred dollars for a gigabyte of hard drive storage. Unfortunately, until the advent of the present invention, these alternative techniques did not allow instantaneous playback of stored data, so use of these less expensive storage devices was not practicable.
Second, the use of volatile memory such as RAM required that all stored sound effects, in their entirety, be reloaded in the event that power to the effects system was interrupted, once again necessitating a lengthy loading process. In response to this limitation, it has become common practice in the industry to never voluntarily shut off such effects systems. Therefore, if power to these systems was ever shut off, it would be quite laborious in many cases to properly reconfigure the systems once power was returned, particularly in light of the many unsaved modifications likely to have been made since the data was last loaded.
Finally, with the ever-increasing demand for higher sampling rates (requiring more data storage space) and the escalating prevalence of sound effects usage in audiovisual works, the aforementioned problems will certainly be compounded in the future, as long as RAM-based effects systems remain the standard.